The world of Atlantic City, N.J., in 1920 is not so far removed from our own in many ways -- houses have electricity, people talk on telephones and drive cars, men wear suits and ties, and women wear shorter skirts.But for all the ways it's similar, it's different in a thousand others, big and small.

Airing Sundays on HBO, the freshman drama "Boardwalk Empire" (already renewed for its second season) lives in this bygone era, and it's the job of such men as production designer Bob Shaw and costume designer John Dunn to bring it to life.

On a chilly April night, Shaw stands on his creation -- a solidly constructed, 300-foot-long recreation of the Boardwalk in 1920 -- and talks about where it all began."People always ask, 'Does this re-create a certain section of the Boardwalk?' " he says. "And the answer is, no. It's greatest hits of certain buildings that we liked. The building over there" -- he gestures toward the Canton Tea Parlor with its large sign advertising "Chop Suey" -- "the Chop Suey building, we just saw it in a photograph, and we just loved it."

He lives on the eighth floor of the Ritz-Carlton Hotel, which on the show is a blend of a real door and lobby just off the Boardwalk with computer-generated upper floors (Nucky's suite is built on a soundstage).

The real Ritz-Carlton, now condos, is a solid-looking brick structure, but the Ritz of "Boardwalk Empire" is light, elegant and fancifully decorated with seashells and mermaids.

Shaw admits its design owes more to Atlantic City's Traymore Hotel, and as for the mermaids, etc., he says, "That's a little bit of Childs Restaurant in Coney Island."

According to Shaw, the Boardwalk, built behind a protective wall of shipping containers in the Greenpoint section of Brooklyn (the sand is real, but the ocean beyond is computer-generated trickery), is perhaps the largest outdoor set constructed in the New York area since before 1920.

Begun early in 2009, it was ready for filming by summer.

But, says Shaw, "when this was covered in snow in the winter, we began to remember why the movie industry talked about moving to the orange groves in California."

While it's difficult to shoot exteriors on the streets -- "It's hard to find more than two buildings in a row that are historically accurate," says Shaw -- interiors of buildings in Brooklyn provide most of the period rooms.

How they're used can be a bit of an irony. The raucous nightclub Babette's is housed inside a meeting room at the John Wesley Methodist Church in the Stuyvesant Heights neighborhood, and a brothel is housed inside a former mansion later turned into a home for senior citizens.

After the locations, perhaps the biggest other production challenge is putting the principal cast and sometimes more than 150 extras at a time into historically accurate garb.

According to costumer Dunn, the clothes for the main cast are made from scratch, using the types of fabrics available at the time (and that includes the underwear). With so many extras to dress, though, Dunn and his team must buy or rent vintage clothes -- and they don't hold up well under the stress of filming.

"We have a shop," he says during a break from supervising men in linen suits and women in filmy dresses for the summer scene being shot, "that just spends time repairing costumes that we've rented. We go to all the vintage shows and buy stuff. Most of our stuff comes from rental houses in California.

"Many of our actors have never worn clothing like this before. It really transforms them."

Dunn is also looking forward to season two, which should carry the show into 1921.

"The hemlines are going to start coming up," he says, "and the men's suits are going to change as well."

Even when he aims to be accurate, Dunn could wind up surprising people whose vision of the 1920s may come only from photographs or old movies, or from clothes that have faded from time and use.

"So much of what we look at is in black and white," he says. "We don't always know what they were using colorwise. Some people look at the color and go, 'Whoa!' "

But in one thing, the show is intentionally inaccurate. The Boardwalk's benches face out to sea, not back toward the crowds and storefronts. Shaw explains that's to allow shots of someone sitting on a bench, with the Boardwalk as a background

"Whereas if we face the benches looking in," he says, "every time we want to film somebody on a bench, we would have to computer-generate the ocean."